Better modularization to exclude plugins

[dlvenable]

Is your feature request related to a problem? Please describe.

DataPrepper should support standard plugin loading, while not always including core plugins. Not all users of DataPrepper need to full set of core plugins. These could be split up so that users can include only the plugins they want.

Describe the solution you'd like

Update data-prepper-core:

• It should depend on: data-prepper-plugins:common
• It should no longer depend on data-prepper-plugins - this includes all the plugins

There are some other things we can consider as well:

• The plugin loading could be moved directly into data-prepper-core if we wish to simplify the project.
• Perhaps rename data-prepper-plugins to data-prepper-core-plugins to indicate that these are the core plugins
• If we want plugin loading to be more dynamic, we could make them non-static, and into interfaces. This may allow for different approaches to loading plugins (ie. from classpath versus a plugin repository)